Clip-level Interaction. We first use sliding window group to generate the action anchors and background anchors with different scales.
Following BMN [1]}, we construct weight term \(w_{i,j} \in \mathbb {R}^{N \times T}\)  via uniformly sampling \(N\)  points between the temporal region for each anchor.
First, we conduct dot product in temporal dimension between \(w_{i,j}\)  and \({F_{a}^{^{\prime }}}\)  with the shape \({C \times N}\)  to generate the action anchor.
Then, we get action anchor sequence \(F_{a}^{c} \in \mathbb {R}^{L \times S}\)  where \(L\)  is number of clip and \(S = C \times N\) .
Similarly, we generate background anchors sequence \(F_{b}^{c}\)  in the same way.
